problems in flow simulation
 

Hello,
iam doing simulation on turbochrger compressor and i have a full turbochager ( compressor & turbine both)
here my questions are:
1: if iam doing simulation on single part , should i enclose the whole part in domain or just a single part on which iam going to find results.
2. i have solid works 14 and got the same problems as mach num and supersonic flow , i just created wizard and i haven't did any meshing , just it meshes automatically .


so please guide me , i will be very thank ful to you